There have been a number of patents in this field in recent years, which describe new hardware solutions to achieving a computer/Internet-controlled house and provide improved control of the energy consumption in the household.
In general the prior art in the computer-controlled house control uses several electricity sensors (one per appliance/wall socket) to monitor the electrical activities in a house. This large number of additional devices is complicated and costly. By basing the system on a single sensor it would be more suitable for retrofitting to existing houses with existing appliances. U.S. Pat. No. 5,572,438 by Ehlers describes a house system, which uses a first and a second microcomputer to monitor and control the energy in the household. The patent mainly describes the hardware required to deliver the improvements—microcompute-r, current sensors, appliance control and communication links to the outside world. The system requires a current sensor on each appliance. The hardware requirements for this system seem excessive and expensive to retrofit into an existing household.
U.S. patent application Ser. No. 2003/0050737 by Osann describes another arrangement of hardware, which suggests changing all or several of the electrical wall sockets within the house. It includes suggestions of including video cameras, intercom, and motion detector and temperature sensor in each of these replacement wall outlets. This appears an excessive use of technology with an extensive requirement for hardware and installation work by skilled electricians. Many of these features will not be valued by householders who are happy to not have video cameras in the house. The main financial saving to the householder is through improved temperature control and the additional systems seem excessive. However, the patent application does describe (in claims 81 and 82) a method whereby all of the house electrical current changes can be monitored from a single location in or near the circuit breakers. This seems a much simpler and cheaper approach, which will suit retrofitting of existing houses. However, this idea can be used more effectively with further analytical/mathematical tools run on a computer and with additional moveable adaptors to which it can communicate, as described herein.
An electronic control system for a house is currently on sale from Honeywell Controls under the registered trade mark Hometronic. The system is described on their web site. The Hometronic system uses a single central controller to determine on and off times for appliances and heating appliances around the house. It can connect to the Internet and be controlled via the web from anywhere in the world. However, it relies on one control device being attached to one appliance to provide on/off control and this makes it an expensive system to retrofit.
U.S. Pat. No. 5,115,967 describes a mathematical method of predicting the transient thermal behaviour of a house climate control system (heating/cooling system).
It is already known to use infrared sensors to determine occupancy in the house and to use this information to control house energy systems. An example of this is given in U.S. Pat. No. 6,324,008.
U.S. patent application Ser. No. 2002/0095269 discloses an appliance monitoring system, in which a subsystem incorporated in each appliance monitors parameters such as the number of cycles and the energy consumption of the appliance. In the event that the appliance needs attention, the system alerts the user or a service centre.
Microchip Technology Inc is a supplier of microchips. They have posted an article entitled “Microchip watt-hour Meter using PIC16C923 and CS5460” on their website discussing how to use one of their chips to make a watt hour meter. The power measurement integrated circuit CS5460 from Cirrus Logic/Crystal Power Measurement is used with the microcontroller PIC16C923 to make a power meter. The CS5460 measures the instantaneous voltage and current four thousand times a second and uses these measurements to compute instantaneous power, V.sub.RMS, I.sub.RMS and accumulated energy. Once the accumulated energy has increased by 10 Watt·seconds a pulse is generated at the output pin (EOUT pin) for counting by another device to form a consumption meter. The article explains how to use this device to record total power consumption.